The present invention relates broadly to protective guards for conduit such as hose, tubing, wire, cable, and fiber optics, and more particularly to a moldable, plastic guard for use as a corrosion-resistant, weight saving replacement for the wire spring guards conventionally used in airbrake tubing coil applications.
When conduit such as hose, tubing, wire, cable, or fiber optics is exposed to certain environmental conditions, physical obstacles, or human abuse, the portion of the conduit so exposed may be protected with an external guard or armor. Such guards typically are formed as a coiled steel wire spring or, alternatively, as an elongate plastic or rubber sleeve or spiral. The coil, sleeve, or spiral is configured as having an inner diameter which is sized to be marginally larger than the outer diameter of the wire or conduit to allow the guard to be installed coaxially over the hose or wire. Guards or armor of such type are shown in commonly-assigned U.S. Pat. No. 6,494,496; and in U.S. Pat. Nos. 6,604,758; 5,857,711; 5,816,622; 5,608,963; 5,346,290; 5,277,227; 4,967,799; 4,876,810; 4,805,933; 4,602,808; 4,446,607; 4,406,852; and 3,926,141; Des. 356,858; and European Pat. Appln. Nos. 824,205; and 655,377. A plastic guard is manufactured by WABCO (Westinghouse Air Brake Co.) GmbH of Hannover, Germany.
Typical applications of guards and coils of such type include the protection of hydraulic hose in construction machinery or plant equipment, and of airbrake tubing coils in tractor trailers rigs and other vehicles. Hoses, tubing, fittings, and other components for these applications are described further in commonly-assigned U.S. Pat. Nos. 6,098,666; 5,024,468; 4,335,908; 4,302,036; 4,288,113; 4,188,051; 4,136,897; 3,907,335; 3,830,531; and in U.S. Pat. Nos. 5,918,640; 5,232,645; 4,009,734; and 3,977,440; and U.K. Pat. Appln. GB 2,239,503. Certain of such components are manufactured commercially by Parker-Hannifin Corporation of Cleveland, Ohio, through its Parflex Division of Ravenna, Ohio, and its Brass Products Division of Otsego, Mich., and by Tectran, Inc., of Mississauga, Ontario, Canada.
Each of the guard types heretofore known in the art offer varying degrees of strain relief and/or cut, crush, abrasion, or kink resistance. In general, steel wire springs offer good kink and abrasion resistance. However, as being formed of a metal, springs are subject to corrosion, have a tendency to scratch paint and other finishes, and are relatively heavy which may impact their use in certain mobile applications. When employed at the connected end of a hose or tubing assembly, the spring conventionally is locked to the end fitting which usually is provided as a multi-component including a body, nut, ferrule, and insert.
Plastic or rubber sleeves or spirals conventionally are manufactured by either extrusion, molding, or spiraling, and are known to be generally lightweight and corrosion resistant. In particular, extruded guards offer long, continuous lengths, but the raw materials suited for extrusion generally are considered to be either too flexible to prevent kinking, or too rigid to prevent flexing of the hose without breaking or kinking the guard absent the addition of strain relief slots. Spiral guards, typically provided as strips of plastic thermoformed about a mandrel into a helical shape, also offer long, variable lengths, but generally do not afford appreciable kink resistance. Molded guards, however, can be formed with the rigidity necessary to prevent kinking.
In view of the foregoing, it is believed that continued improvements in guard constructions, and particularly in molded constructions, for wire and conduit tubing coil assemblies would be well-received by the transportation, construction, and other industries involved.